Resource exhaustion in Cisco iOS Xr Software
CVE-2025-20340
A vulnerability in the Address Resolution Protocol (ARP) implementation of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to trigger a broadcast storm, leading to a denial of service (DoS) condition on an affected device. This vulnerability is due to how Cisco IOS XR Software processes a high, sustained rate of ARP traffic hitting the management interface. Under certain conditions, an attacker could exploit this vulnerability by sending an excessive amount of traffic to the management interface of an affected device, overwhelming its ARP processing capabilities. A successful exploit could result in degraded device performance, loss of management connectivity, and complete unresponsiveness of the system, leading to a DoS condition.
Vulnerability class: DoS (Denial of Service)
EPSS: 0.006 (44.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.
Affected products
- Cisco Ios Xr Software — versions 6.5.3, 6.5.29, 6.5.1
Weakness classification (CWE)
Public proof-of-concept exploits
References
Frequently asked questions
- What is CVE-2025-20340?
- CVE-2025-20340 is a high-severity vulnerability in Cisco iOS Xr Software, classified under Uncontrolled Resource Consumption. CVSS score: 7.4/10. Published 2025-09-10.
- How severe is CVE-2025-20340?
- High severity. CVSS v3 base score is 7.4 out of 10.
- Is CVE-2025-20340 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.